1. Field of the Invention
The present invention relates to a magnetic memory element and a magnetic memory device, particularly a magnetic memory element and a magnetic memory device capable of rewriting information by flowing spin-polarized electrons to the magnetic element.
2. Description of the Related Art
As a nonvolatile magnetic memory device of the next generation, a MRAM (Magnetic Random Access Memory) device has drawn attention. The MRAM device is a nonvolatile magnetic memory device which can store nonvolatile data using a plurality of memory cells of thin film magnetic layers formed in a semiconductor integrated circuit and at the same time which allows random access to the respective memory cells.
Each of such memory cells includes a magnetoresistive element with a sandwich structure formed by arranging a fixing layer of a ferromagnetic layer having a fixed magnetization direction and a recording layer of a ferromagnetic layer having a magnetization direction varied in accordance with an outside magnetic field while inserting a nonmagnetic layer between them. The magnetoresistive element stores data while making the data relevant to the alteration of electric resistance values generated correspondingly to the alteration of the magnetization direction of the recording layer. The alteration of the electric resistance values can be classified into a tunnel magneto resistive effect and a giant magneto resistive effect in accordance with the principles and it has been known well that the capability of the MRAM device can remarkably be improved by using a magnetoresistive element based on the tunnel magneto resistive effect.
STT-MRAM (Spin Transfer Torque-MRAM) using a method for inverting the magnetization direction of a memory layer by flowing spin-polarized electrons to the magnetic layer as a method for inverting the magnetization of the memory layer is reported (e.g., F. J. Albert, et al., Appl. Phy. Lett. Vol. 77, P. 3809 (2000), Y. Huai, et al., Appl. Phy. Lett. Vol. 84, P. 3118 (2004)). Such magnetization inversion manner by spin injection is based on the principle that the spin can be transmitted by interaction of the spin angular momentum of electrons with the angular momentum of the magnetic layer. It is characterized in that as the size of the memory cell becomes smaller, the current needed for magnetization inversion of the memory layer is made smaller and thus this method can be said to be a memory method suitable for a nonvolatile magnetic memory device with high capacity.